| 33 | | Calibration files are produced by Specim when they do maintenance on the instrument. |
| | 33 | Calibration files are produced by Specim when they do maintenance on the instrument. FSF is starting to do this now (first test attempt in Dec 2007). |
| | 34 | |
| | 35 | A brief description of the procedure: |
| | 36 | 1. checking wavelength alignment (can be done in imaging mode - 512x?) - this checks that the light is being measured at the correct wavelengths (value unimportant) |
| | 37 | 1. pick a suitable calibrated light source (e.g. big lamp) and flood out the CCD evenly |
| | 38 | 1. examine the output to see if there are spikes (value unimportant, only position in spectrum counts) in the appropriate emission bands |
| | 39 | 1. repeat with a filter and look for troughs (value unimportant, only position in spectrum counts) in the appropriate absorption bands |
| | 40 | 1. this method can also be used to verify an existing calibration to some extent |
| | 41 | 1. full calibration |
| | 42 | 1. switch the instrument to calibration mode (1024x1024 pixels) |
| | 43 | 1. point the instrument into a calibrated integrating sphere, at a distance where there won't be too many reflections back into the sphere, but close enough to evenly illuminate the whole CCD |
| | 44 | 1. take measurements at the various settings |
| | 45 | 1. (post processing) calculate offset and gain constants |